The present disclosure relates generally to mixed acid assemblies for cleaning the gas passages of showerhead electrodes that are used as excitation electrodes in plasma processing systems. Although the context of the present disclosure is not limited to particular types of showerhead electrodes or the context in which the showerhead electrodes to be cleaned have been used, for the purposes of illustration, the mixed acid assemblies are illustrated herein with reference to a mono silicon-based electrode having a disc-shape with concentrically arranged gas passages. Those practicing the embodiments described herein will find that some of the mixed acid assemblies proposed herein will enjoy favorable utility in the context of a variety of types of electrodes and non-electrodes.
FIG. 1 illustrates a mixed acid assembly coupled to a showerhead electrode having a disc-shape. FIG. 3 illustrates a showerhead electrode in an exploded view. Further teachings regarding the structure of showerhead electrodes and electrode assemblies similar to that illustrated in FIGS. 1 and 3 can be found in US Pub. Nos. 2007/0068629, 2007/0235660, and 2007/0284246, pertinent portions of which are incorporated herein by reference. Additional related teachings can be found in U.S. Pat. Nos. 6,073,577, 6,148,765, 6,194,322, 6,245,192, and 6,376,385, and US Pub. No. 2005/0241765.